Engine Purge Control Accuracy via Dynamic Learning
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Solution Overview
Problem
The air-fuel ratio in an engine device tends to be unstable during the second purge due to the longer time for evaporated fuel gas to reach the combustion chamber and fluctuations in supercharging pressure, leading to low accuracy in the purge concentration-related value.
Innovation Solution
The engine device updates the purge concentration-related value using a smaller absolute value during the second purge and allows a larger update value when switching to the first purge until a predetermined condition is met, and sets the threshold value based on the air-fuel ratio deviation and the number of times learned, to correct deviations in the purge concentration-related value.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the purge concentration-related value is learned using the same update method during both first purge and second purge, then the learning process is simple and consistent, but the accuracy of the purge concentration-related value decreases during the second purge due to air-fuel ratio instability
Solution Approach 1:
The patent applies dynamics by making the update amount of the purge concentration-related value variable based on the purge mode. During the first purge, a first update amount is used, while during the second purge, a second update amount (smaller than the first) is used. This dynamic adjustment of the update amount according to operating conditions resolves the contradiction by maintaining high accuracy during the unstable second purge while keeping the control logic manageable through predefined update rules.
2Productivity
If a larger update amount is used during the second purge to correct deviations faster, then the response speed improves, but the accuracy of the learned value decreases due to air-fuel ratio fluctuations
Solution Approach 1:
The patent applies parameter changes by adjusting the update amount parameter based on the purge mode. During the second purge, when air-fuel ratio fluctuations occur, a smaller update amount is used to prevent excessive deviation correction that would reduce accuracy. This parameter adjustment resolves the contradiction by balancing response speed and accuracy - the system responds to deviations while maintaining learned value accuracy through the smaller update amount during unstable conditions.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach mitigates the decrease in accuracy of the purge concentration-related value during the second purge, allowing for more appropriate control of the fuel injection valve and required injection amount.
Implementation Method 1
an ejector that generates a negative pressure using a supercharging pressure from the turbocharger
Data Source
AI summary
During execution of a purge, a purge concentration-related value is learned based on an air-fuel ratio deviation that is a deviation of an air-fuel ratio detected by an air-fuel ratio sensor from a required air-fuel ratio. In this case, the purge concentration-related value is updated using an update amount with a smaller absolute value when the purge is a second purge of supplying evaporated fuel gas to an intake pipe through a second purge passage than when the purge is a first purge of supplying the evaporated fuel gas to the intake pipe through a first purge passage.